The development of an instrumented tamp-filling capsule machine I Instrumentation of a Bosch GKF 400S machine and feasibility study

The instrumentation of capsule filling machines operating by the tamp-filli ng principle has been described only once, using strain gauges. In the pres ent paper the instrumentation of a Bosch GKF 400S tamp-filling machine has been described using a prototype of a pneumatic tamping head equipped with a piezoelectric force transducer. The pneumatic system replaces the convent ional springs situated between tamping pins and upper part of the tamping h ead. Via a feedback switch valve, the air pressure inside the pneumatic cha mber can be regulated. This provides a potential mechanism for feedback con trol of capsule fill weight during continuous capsule filling. It was found that the use of the pneumatic tamping head is limited to the control of fi ll weight during tamping. Major adjustments of fill weight at the set-up st age of the machine should be made by alteration of the tamping pin and powd er bed height settings. The principles of capsule fill weight control by co ntinuous monitoring of tamping forces have been established, but the transf er of the system to full industrial use requires further development of the prototype by the machine manufacturer. (C) 2000 Elsevier Science B.V. All rights reserved.